Amplification and expression of a multidrug resistance gene in human glioma cell lines.
Two human glioma cell lines were examined for multidrug resistance (MDR). A vincristine (VCR)-resistant glioma cell line showed a cross resistance to Adriamycin (doxorubicin, ADR) and etoposide (VP-16) to varying extents, suggesting the presence of MDR; the resistance to VCR was considerably decreased by calcium entry blockers. On the other hand, another VCR-sensitive glioma cell line exhibited no cross resistance to ADR or VP-16. Double minute chromosomes and homogeneously staining regions as well as clonal aberrations of chromosome 7 were not observed in cytogenetic studies of multidrug-resistant and multidrug-sensitive glioma cell lines. In Northern and Southern blot analyses, MDR gene 1 (MDR1) messenger ribonucleic acid (mRNA) was shown to be overexpressed without any amplification of the MDR1 gene in multidrug-resistant glioma cell lines as compared to multidrug-sensitive glioma cell lines. It would be reasonable to suggest that amplification of the MDR1 gene may not be a sine qua non for acquisition of MDR and that the MDR1 mRNA level may be correlated with the extent of MDR.
Matsumoto
T
T
Department of Neurosurgery, Hyogo College of Medicine, Japan.
Tani
E
E
Kaba
K
K
Kochi
N
N
Shindo
H
H
Yamamoto
Y
Y
Sakamoto
H
H
Furuyama
J
J
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000235:genetics; D004317:Doxorubicin / Q000627:therapeutic use; D004351:Drug Resistance / Q000235:genetics*; D005047:Etoposide / Q000627:therapeutic use; D005784:Gene Amplification; D015870:Gene Expression / Q000187:drug effects; D005910:Glioma / Q000188:drug therapy* / Q000235:genetics; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000627:therapeutic use
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D014750:Vincristine; D005047:Etoposide; D004317:Doxorubicin